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Homework Help: Changing Units Problem

  1. Jun 17, 2005 #1
    Hello, perhaps you could help with a problem.

    Suppose a pulsar rotates once every 1.400 806 448 872 75 + or - 5 ms, where the trailing + or - 5 indicates the uncertainty in the last decimal place (it does not mean + or - 5ms).

    a. How many times does the pulsar rotate in 30.0 days?
    I solved this one, 30days(60s/min)(60min/hr)(24hr/day) = 1.85(10^9)

    b. How much time does the pulsar take to rotate 2.0(10^6) times?
    (Give your answer to at least 4 decimal places.)

    c. What is the associated uncertainty of this time?

    It's these last two that are giving me issues, for b. I figured you just multiply the amount of rotations by the time it takes to rotate, I came up with 2801.61 s but according to webassign is wrong. I even stuffed it with 2 zeros to go out 4 decimal places. I'm just not sure about c, though I need the answer to b. to start.
     
  2. jcsd
  3. Jun 17, 2005 #2

    HallsofIvy

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  4. Jun 17, 2005 #3
    Thank you for your help, you've led me to the correct answer. It is 2801.6128977455, you must have left out the (ms) or 10^-3 when multiplying. My calculator was only set up to display 6 digits. Thanx again.
     
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